Pub Date : 2026-06-01Epub Date: 2026-01-20DOI: 10.1016/j.optcom.2026.132917
Yonghong Wang , Zhuoyan Wang , Yanfeng Yao , Junrui Li
To address the problems of fringe merging and loss of fringe edge information during the denoising of high-density fringe patterns in digital speckle pattern interferometry (DSPI), which seriously affects the phase reconstruction and measurement precision, a hierarchical adaptive curvelet thresholding with sine-cosine transform (HACuT) is proposed in this paper. By incorporating subband-wise noise energy estimation in the curvelet domain, local statistical constraints derived from clean image curvelet coefficients, and hierarchical scale-dependent adjustment, an adaptive thresholding scheme is constructed to enable precise and robust regulation of curvelet coefficients. Moreover, a smooth thresholding function based on the hyperbolic tangent is designed to enhance denoising stability. Simulation and experimental results demonstrate that the proposed method effectively suppresses noise, preserves fringe edge integrity, and maintains high computational efficiency, confirming its practical applicability.
{"title":"Multi-scale based approach for denoising digital speckle pattern interferometry fringe patterns using curvelet thresholding","authors":"Yonghong Wang , Zhuoyan Wang , Yanfeng Yao , Junrui Li","doi":"10.1016/j.optcom.2026.132917","DOIUrl":"10.1016/j.optcom.2026.132917","url":null,"abstract":"<div><div>To address the problems of fringe merging and loss of fringe edge information during the denoising of high-density fringe patterns in digital speckle pattern interferometry (DSPI), which seriously affects the phase reconstruction and measurement precision, a hierarchical adaptive curvelet thresholding with sine-cosine transform (HACuT) is proposed in this paper. By incorporating subband-wise noise energy estimation in the curvelet domain, local statistical constraints derived from clean image curvelet coefficients, and hierarchical scale-dependent adjustment, an adaptive thresholding scheme is constructed to enable precise and robust regulation of curvelet coefficients. Moreover, a smooth thresholding function based on the hyperbolic tangent is designed to enhance denoising stability. Simulation and experimental results demonstrate that the proposed method effectively suppresses noise, preserves fringe edge integrity, and maintains high computational efficiency, confirming its practical applicability.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132917"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-20DOI: 10.1016/j.optcom.2026.132929
Fanmiao Meng, Weiwei Yu
and are the fundamental models in intense laser field, facilitating the investigation of attosecond electron dynamics, the observation of nuclear wave packet evolution, and the implementation of frequency-modulated high-order harmonic generation. In this work, the high-order harmonic generation dynamics of and , under terahertz field assistance and the nuclear motion, were investigated by using numerical solutions of the non-Born–Oppenheimer time-dependent Schrödinger equation. Terahertz assistance increases the peak intensity of the central electric field while maintaining the shape of the electric field, consequently significantly extending the harmonic cutoff range and generating three distinct plateau regions. Upon considering non-Born–Oppenheimer approximation, the asymmetry of the electron cloud amplifies the interaction between electrons and nuclei, the nuclear motion is relatively slow, so the nuclei remain within the Franck–Condon region. Thus, the efficiency of the harmonic is three orders of magnitude greater than that of . These findings provide new perspectives on the microscopic principles of terahertz-assisted high-order harmonic generation and clarify the impact of nuclear motion on this phenomenon.
{"title":"Investigating the effect of nuclear motion on the high-order harmonic generation efficiency of H2+ and HD+ molecules under terahertz assistance","authors":"Fanmiao Meng, Weiwei Yu","doi":"10.1016/j.optcom.2026.132929","DOIUrl":"10.1016/j.optcom.2026.132929","url":null,"abstract":"<div><div><span><math><msubsup><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> and <span><math><msup><mrow><mi>HD</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span> are the fundamental models in intense laser field, facilitating the investigation of attosecond electron dynamics, the observation of nuclear wave packet evolution, and the implementation of frequency-modulated high-order harmonic generation. In this work, the high-order harmonic generation dynamics of <span><math><msubsup><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> and <span><math><msup><mrow><mi>HD</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>, under terahertz field assistance and the nuclear motion, were investigated by using numerical solutions of the non-Born–Oppenheimer time-dependent Schrödinger equation. Terahertz assistance increases the peak intensity of the central electric field while maintaining the shape of the electric field, consequently significantly extending the harmonic cutoff range and generating three distinct plateau regions. Upon considering non-Born–Oppenheimer approximation, the asymmetry of the electron cloud amplifies the interaction between electrons and nuclei, the nuclear motion is relatively slow, so the nuclei remain within the Franck–Condon region. Thus, the efficiency of the <span><math><msubsup><mrow><mi>H</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>+</mo></mrow></msubsup></math></span> harmonic is three orders of magnitude greater than that of <span><math><msup><mrow><mi>HD</mi></mrow><mrow><mo>+</mo></mrow></msup></math></span>. These findings provide new perspectives on the microscopic principles of terahertz-assisted high-order harmonic generation and clarify the impact of nuclear motion on this phenomenon.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132929"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-22DOI: 10.1016/j.optcom.2026.132948
Xiaoqin Bai , Min Han , Rongcao Yang
In this work, we present a versatile method for achieving unidirectional and bidirectional soliton conversion, together with controllable oscillation and helical rotation of solitons by introducing longitudinally alternating inhomogeneous potentials into fractional diffraction system. Across diverse alternating potentials, the soliton undergoes unidirectional conversion into distinct and tailored states, including periodic and Hermite-Gaussian solitons, with the conversion efficiency jointly governed by Lévy index and potential parameters. Under the selected longitudinal inhomogeneous modulation, judiciously engineering the alternating second potential drives bidirectional conversion of diverse solitons—ring and necklace solitons among them. Additionally, the controlled oscillation and helical rotation of soliton pairs in alternating inhomogeneous fractional diffraction system are examined in detail. The study enriches the research of potential engineering in fractional diffraction systems, and holds promise for revealing novel physical phenomena—driven by the interplay of fractional Lévy index and dynamic potentials—that may be difficult to be observed in conventional integer-order diffraction systems. In addition, the steerable soliton conversion, oscillation and helical rotation open an excellent prospect for optical switching, optical modulation and other related technologies.
{"title":"Conversion, oscillation and helical rotation of solitons in alternating inhomogeneous fractional diffraction system","authors":"Xiaoqin Bai , Min Han , Rongcao Yang","doi":"10.1016/j.optcom.2026.132948","DOIUrl":"10.1016/j.optcom.2026.132948","url":null,"abstract":"<div><div>In this work, we present a versatile method for achieving unidirectional and bidirectional soliton conversion, together with controllable oscillation and helical rotation of solitons by introducing longitudinally alternating inhomogeneous potentials into fractional diffraction system. Across diverse alternating potentials, the soliton undergoes unidirectional conversion into distinct and tailored states, including periodic and Hermite-Gaussian solitons, with the conversion efficiency jointly governed by Lévy index and potential parameters. Under the selected longitudinal inhomogeneous modulation, judiciously engineering the alternating second potential drives bidirectional conversion of diverse solitons—ring and necklace solitons among them. Additionally, the controlled oscillation and helical rotation of soliton pairs in alternating inhomogeneous fractional diffraction system are examined in detail. The study enriches the research of potential engineering in fractional diffraction systems, and holds promise for revealing novel physical phenomena—driven by the interplay of fractional Lévy index and dynamic potentials—that may be difficult to be observed in conventional integer-order diffraction systems. In addition, the steerable soliton conversion, oscillation and helical rotation open an excellent prospect for optical switching, optical modulation and other related technologies.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132948"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-23DOI: 10.1016/j.optcom.2026.132946
Xiaolei Kuang , Xijun Ren
This study conducts a comprehensive benchmarking analysis of neural-network-based quantum state tomography on a four-photon entangled system, systematically evaluating the performance of three variational architectures: the positive-real ansatz, the pure-state ansatz, and the purification ansatz. Our experimental findings illustrate the following: the positive-real ansatz attains a fidelity exceeding 99% for Z-basis measurements, though its performance is highly sensitive to the choice of measurement basis; the pure-state ansatz, which is based on a restricted Boltzmann machine, achieves a fidelity of over 99% while utilizing merely 31% of the conventional measurement bases, thereby demonstrating remarkable measurement efficiency; in contrast, the purification ansatz exhibits notable fragility during optimization and high sensitivity to noise. This work offers essential guidance for the selection of suitable neural-network architectures in quantum state tomography and their potential extension to large-scale quantum systems.
{"title":"Neural-network quantum state tomography in four-photon entanglement systems","authors":"Xiaolei Kuang , Xijun Ren","doi":"10.1016/j.optcom.2026.132946","DOIUrl":"10.1016/j.optcom.2026.132946","url":null,"abstract":"<div><div>This study conducts a comprehensive benchmarking analysis of neural-network-based quantum state tomography on a four-photon entangled system, systematically evaluating the performance of three variational architectures: the positive-real ansatz, the pure-state ansatz, and the purification ansatz. Our experimental findings illustrate the following: the positive-real ansatz attains a fidelity exceeding 99% for Z-basis measurements, though its performance is highly sensitive to the choice of measurement basis; the pure-state ansatz, which is based on a restricted Boltzmann machine, achieves a fidelity of over 99% while utilizing merely 31% of the conventional measurement bases, thereby demonstrating remarkable measurement efficiency; in contrast, the purification ansatz exhibits notable fragility during optimization and high sensitivity to noise. This work offers essential guidance for the selection of suitable neural-network architectures in quantum state tomography and their potential extension to large-scale quantum systems.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132946"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-27DOI: 10.1016/j.optcom.2026.132962
Chenlong Dai, Yang Wang, Jiantai Dou
Accurate axial distance calibration is pivotal for high-precision ptychography. The conventional dichotomy-based approach (dPIE) suffers from slow convergence and computationally intensive preprocessing. Here, we introduce a hybrid framework: A linear model analytically reconstructs high-fidelity initial object/probe distributions, integrated with an optimized dichotomous scheme for axial refinement. This strategy enables single-iteration processing at each candidate distance without preprocessing overhead, which effectively overcomes key limitations of dPIE. Validated on standard and biological specimens, the framework can drastically reduce the correction time. By leveraging total variation to exponentially narrow the search interval, the rapid convergence is achieved with minimal computation. This method provides an efficient solution for axial distance calibration in ptychographic systems.
{"title":"Fast calibration method of axial distance error in ptychography based on linear model for initial object reconstruction","authors":"Chenlong Dai, Yang Wang, Jiantai Dou","doi":"10.1016/j.optcom.2026.132962","DOIUrl":"10.1016/j.optcom.2026.132962","url":null,"abstract":"<div><div>Accurate axial distance calibration is pivotal for high-precision ptychography. The conventional dichotomy-based approach (dPIE) suffers from slow convergence and computationally intensive preprocessing. Here, we introduce a hybrid framework: A linear model analytically reconstructs high-fidelity initial object/probe distributions, integrated with an optimized dichotomous scheme for axial refinement. This strategy enables single-iteration processing at each candidate distance without preprocessing overhead, which effectively overcomes key limitations of dPIE. Validated on standard and biological specimens, the framework can drastically reduce the correction time. By leveraging total variation to exponentially narrow the search interval, the rapid convergence is achieved with minimal computation. This method provides an efficient solution for axial distance calibration in ptychographic systems.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132962"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-22DOI: 10.1016/j.optcom.2026.132922
Ajun Shao , Shuting Ma , Xingyu Zhang , Zhuang Zhao , Baohui Guo , Mingze Ma , Jing Han , Yong Peng , Yi Zhang , Lianfa Bai , Guohua Gu , Xin Liu
Near-infrared hyperspectral images (NIR-HSIs, 900–1700 nm) offer rich spectral information and strong haze-penetrating capability, but their performance is often constrained by sensor noise, leading to low signal-to-noise ratio (SNR), diminished contrast, and texture degradation. In contrast, RGB cameras offer higher SNR and richer texture details while being low-cost and widely accessible, thus serving as effective priors to enhance reconstruction of NIR-HSI. This paper propose an RGB-Guided Phase-Aware Hybrid Prior (RGB-PAHP) method within a dual-camera system, where an RGB camera is integrated into a coded aperture snapshot spectral imaging (CASSI) architecture. A multi-scale RGB feature extraction module (RGB-FE) is designed to fully exploit spatial details from RGB images, effectively guiding the reconstruction of NIR-HSI with high SNR. Furthermore, the method employs a deep unfolding network entirely based on multilayer perceptron (MLP), and introduces a Degradation-Aware Residual Gradient Descent (DARGD) module to estimate the residual of the sensing matrix and degradation matrix . The iterative process is divided into shallow spatial–spectral feature extraction and deep texture refinement, balancing reconstruction quality and computational efficiency. Experimental results demonstrate that RGB-PAHP outperforms existing methods in terms of PSNR, SSIM, and SAM, thereby validating its superiority in NIR-HSI reconstruction.
{"title":"RGB-guided phase-aware hybrid prior network for snapshot near-infrared hyperspectral imaging","authors":"Ajun Shao , Shuting Ma , Xingyu Zhang , Zhuang Zhao , Baohui Guo , Mingze Ma , Jing Han , Yong Peng , Yi Zhang , Lianfa Bai , Guohua Gu , Xin Liu","doi":"10.1016/j.optcom.2026.132922","DOIUrl":"10.1016/j.optcom.2026.132922","url":null,"abstract":"<div><div>Near-infrared hyperspectral images (NIR-HSIs, 900–1700 nm) offer rich spectral information and strong haze-penetrating capability, but their performance is often constrained by sensor noise, leading to low signal-to-noise ratio (SNR), diminished contrast, and texture degradation. In contrast, RGB cameras offer higher SNR and richer texture details while being low-cost and widely accessible, thus serving as effective priors to enhance reconstruction of NIR-HSI. This paper propose an RGB-Guided Phase-Aware Hybrid Prior (RGB-PAHP) method within a dual-camera system, where an RGB camera is integrated into a coded aperture snapshot spectral imaging (CASSI) architecture. A multi-scale RGB feature extraction module (RGB-FE) is designed to fully exploit spatial details from RGB images, effectively guiding the reconstruction of NIR-HSI with high SNR. Furthermore, the method employs a deep unfolding network entirely based on multilayer perceptron (MLP), and introduces a Degradation-Aware Residual Gradient Descent (DARGD) module to estimate the residual of the sensing matrix <span><math><mrow><mi>Φ</mi></mrow></math></span> and degradation matrix <span><math><mrow><mover><mi>Φ</mi><mo>ˆ</mo></mover></mrow></math></span>. The iterative process is divided into shallow spatial–spectral feature extraction and deep texture refinement, balancing reconstruction quality and computational efficiency. Experimental results demonstrate that RGB-PAHP outperforms existing methods in terms of PSNR, SSIM, and SAM, thereby validating its superiority in NIR-HSI reconstruction.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132922"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-27DOI: 10.1016/j.optcom.2025.132805
Xiang Sui , Ying Shang , Sheng Huang , Wenan Zhao , Xiaohan Qiao , Guangqiang Liu , Chunmei Yao , Shouling Liu , Na Wan , Xianggui Kong , Hong Zhao , Fengming Mou , Zhengying Li , Weitao Wang , Chen Wang , Gangding Peng
{"title":"Corrigendum to “Coherent fading suppression method in the COTDR system based on multi-band filtering” [Opt. Commun. 583 (2025) 131696]","authors":"Xiang Sui , Ying Shang , Sheng Huang , Wenan Zhao , Xiaohan Qiao , Guangqiang Liu , Chunmei Yao , Shouling Liu , Na Wan , Xianggui Kong , Hong Zhao , Fengming Mou , Zhengying Li , Weitao Wang , Chen Wang , Gangding Peng","doi":"10.1016/j.optcom.2025.132805","DOIUrl":"10.1016/j.optcom.2025.132805","url":null,"abstract":"","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132805"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-09DOI: 10.1016/j.optcom.2026.132897
Okikiade Adewale Layioye , Pius Adewale Owolawi , Chunling Tu , Etienne Van Wyk , Joseph Sunday Ojo
Free-Space Optical (FSO) communication offers a powerful solution for high-speed and long-distance data transmission, but the quality of the performance is critically dependent on atmospheric conditions. This paper presents a comprehensive, data-driven framework for characterizing and predicting atmospheric attenuation from fog and rain for FSO links. Our analysis reveals a distinct non-Gaussian distribution for attenuation, with a small number of severe fog events dominating link degradation. The mean total attenuation for all cities is significantly higher with maximum values reaching over 170 dB/km, whereas rain attenuation peaks below 4 dB/km. A link budget analysis with a 26.6 dB fade margin demonstrates that for this configuration, rain is a negligible factor, with fog being the sole contributor to link outage. To address the challenge of real-time link management, a Random Forest (RF) regressor technique was trained to predict total attenuation from visibility and rain data. A systematic dual-split modeling approach (chronological time-forward splits and random shuffled splits) was employed to provide a comprehensive performance evaluation and to assess the RF model's performance both under general, independent and identically distributed assumptions and under realistic time-series forecasting conditions. The shuffled-split models, trained on a random mix of data, achieved a near-perfect coefficient of determination ( >0.9997) and very low root mean square error (RMSE ≈ 0.0300 dB/km) for most cities, confirming the model's fundamental ability to learn the underlying relationships. Feature importance analysis revealed visibility as the overwhelmingly dominant predictor, accounting for over 99 % of the model's predictive power. This work demonstrates that the proposed framework, augmented by machine learning, is a versatile and reliable tool for preliminary site assessment, link-outage probability calculation, and real-time link margin management in FSO networks. The findings provide a critical foundation for the deployment of FSO infrastructure in the climatically diverse South African landscape.
{"title":"Machine learning-based enhanced visibility framework and predictive fog- and precipitation-induced attenuation modeling of subtropical free-space optical communication links","authors":"Okikiade Adewale Layioye , Pius Adewale Owolawi , Chunling Tu , Etienne Van Wyk , Joseph Sunday Ojo","doi":"10.1016/j.optcom.2026.132897","DOIUrl":"10.1016/j.optcom.2026.132897","url":null,"abstract":"<div><div>Free-Space Optical (FSO) communication offers a powerful solution for high-speed and long-distance data transmission, but the quality of the performance is critically dependent on atmospheric conditions. This paper presents a comprehensive, data-driven framework for characterizing and predicting atmospheric attenuation from fog and rain for FSO links. Our analysis reveals a distinct non-Gaussian distribution for attenuation, with a small number of severe fog events dominating link degradation. The mean total attenuation for all cities is significantly higher with maximum values reaching over 170 dB/km, whereas rain attenuation peaks below 4 dB/km. A link budget analysis with a 26.6 dB fade margin demonstrates that for this configuration, rain is a negligible factor, with fog being the sole contributor to link outage. To address the challenge of real-time link management, a Random Forest (RF) regressor technique was trained to predict total attenuation from visibility and rain data. A systematic dual-split modeling approach (chronological time-forward splits and random shuffled splits) was employed to provide a comprehensive performance evaluation and to assess the RF model's performance both under general, independent and identically distributed assumptions and under realistic time-series forecasting conditions. The shuffled-split models, trained on a random mix of data, achieved a near-perfect coefficient of determination (<span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span> >0.9997) and very low root mean square error (RMSE ≈ 0.0300 dB/km) for most cities, confirming the model's fundamental ability to learn the underlying relationships. Feature importance analysis revealed visibility as the overwhelmingly dominant predictor, accounting for over 99 % of the model's predictive power. This work demonstrates that the proposed framework, augmented by machine learning, is a versatile and reliable tool for preliminary site assessment, link-outage probability calculation, and real-time link margin management in FSO networks. The findings provide a critical foundation for the deployment of FSO infrastructure in the climatically diverse South African landscape.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"606 ","pages":"Article 132897"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145981659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-27DOI: 10.1016/j.optcom.2026.132966
Maoni Chen , Aimin Liu , Shangde Zhou , Jianqiu Cao , Qi Zhang , Zhihe Huang , Zilun Chen , Zefeng Wang , Jinbao Chen
A 1.5-kW large-core step-index Yb-doped fiber amplifier operating near 980 nm is firstly demonstrated, to the best of our knowledge, by means of broadening the signal bandwidth to suppress in-band amplified spontaneous emission (ASE) around 980 nm. The signal bandwidth covering from 974 nm to 980 nm is achieved using a home-made seed oscillator with a dual low-reflectivity fiber Bragg grating (LR-FBG) configuration. The record 1.546-kW output power was achieved with a slope efficiency of 71.5 % (with respect to the launched pump power) which should also be the highest achieved by the step-index double-cladding Yb-doped fiber. The power ratio of in-band ASE was suppressed to below 1 %, while the ASE around 1030 nm was also 27.8-dB suppressed. This amplifier can strongly drive the power up-scaling of high-power fiber lasers and amplifiers as high-power cladding-pumping source, and thus can have significant impact on application fields involving high-power fiber lasers and amplifiers.
{"title":"Demonstration of 1.5-kW large-core step-index Yb-doped fiber amplifier near 980 nm","authors":"Maoni Chen , Aimin Liu , Shangde Zhou , Jianqiu Cao , Qi Zhang , Zhihe Huang , Zilun Chen , Zefeng Wang , Jinbao Chen","doi":"10.1016/j.optcom.2026.132966","DOIUrl":"10.1016/j.optcom.2026.132966","url":null,"abstract":"<div><div>A 1.5-kW large-core step-index Yb-doped fiber amplifier operating near 980 nm is firstly demonstrated, to the best of our knowledge, by means of broadening the signal bandwidth to suppress in-band amplified spontaneous emission (ASE) around 980 nm. The signal bandwidth covering from 974 nm to 980 nm is achieved using a home-made seed oscillator with a dual low-reflectivity fiber Bragg grating (LR-FBG) configuration. The record 1.546-kW output power was achieved with a slope efficiency of 71.5 % (with respect to the launched pump power) which should also be the highest achieved by the step-index double-cladding Yb-doped fiber. The power ratio of in-band ASE was suppressed to below 1 %, while the ASE around 1030 nm was also 27.8-dB suppressed. This amplifier can strongly drive the power up-scaling of high-power fiber lasers and amplifiers as high-power cladding-pumping source, and thus can have significant impact on application fields involving high-power fiber lasers and amplifiers.</div></div>","PeriodicalId":19586,"journal":{"name":"Optics Communications","volume":"607 ","pages":"Article 132966"},"PeriodicalIF":2.5,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-06-01Epub Date: 2026-01-23DOI: 10.1016/j.optcom.2026.132907
Xuefeng Shi , Peng Lang , Boyu Ji , Zhenlong Zhao , Yang Xu , Xiaowei Song , Jingquan Lin
Non-diffracting Olver surface plasmon polaritons (SPPs) exhibit unique characteristics of anti-disturbance and self-bending propagation, effectively reducing diffraction loss and extend the propagation distance of the main lobe. In this work, we design a polarization- and wavelength-sensitive composite nanoarray structure that enables flexible and active control of the excitation and bending direction of the Olver SPP main lobe in four distinct directions. Specifically, changing the polarization state of the incident light enables tuning the directional excitation of the Olver SPP main lobe, while varying the incident wavelength allows the precise control of its excitation direction along the upper or lower part of the structure. Quantitative analysis based on the extinction ratio demonstrates the excellent directional excitation capability of the proposed structure. Furthermore, the diffraction-free and self-healing properties of Olver SPPs are verified through the extraction of amplitude distribution curves along their propagation trajectories with the introduction of obstacles. These findings provide a promising strategy for advancing applications in optical tweezers, information routing, and plasmonic functional devices.
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